Equipment for machining, cutting, and welding in which the tool, for example a welding torch, an oxygen cutting head, for thermal cutting, a chisel, a milling cutter, a nibbling machine automatically follows the path of a welding bevel, no matter what its path, are known. The processes used to detect the position of the bevel and to produce a position control signal, acting directly or by means of an amplification relay, are diverse. Actually, mechanical, magnetic, optical, pneumatic and still other tracers are already used. But these apparatus are delicate, their adjustment is difficult. Their operation is often random and maintenance expensive, mainly because of the very harsh conditions of use: high temperatures, light, fumes, noise, etc. prevailing in the vicinity of the electric welding arc, i.e., precisely in a place where the apparatus must operate.
The object of this invention consists in an improvement to this type of apparatus and relates more particularly to an optical apparatus for detecting the position of a reference line formed by a stop located on the edge of a sheet, respectively of a metal or other, sheet of a copying template, of the edge of a line of sufficient width drawn on a support, the optical apparatus carried by an arm and comprising a light emitter whose wavelength can be selected in the area corresponding to visible light or in that of the infrared, this emitter producing a light ray which travels a first incident axis, falls in the shape cut in various directions, particularly in that of a second axis of diffused light connecting this point to a receiver whose surface consists of a large number of cells, each being sensitive to the radiation received and producing an electric signal as a function of its brightness, the group of signals received by the receiver supplying data entering into an electric apparatus acting on the elements carrying the optical apparatus so that the spot of light falling on the reference line whose path can be rectilinear or curvilinear, follows the reference line during the advancing of the operation in progress, by keeping the arrangement of the reference line and of the optical apparatus equal to an instruction value which can be suited to the nature of the operation in progress, the movements of the optical apparatus controlling the concomitant movements of a tool so that this tool follows a path homologous to the reference line, characterized in that the position in relation to the receiver of the bright spot diffused on the receiver by the spot falling on the reference line, constitutes on adjustment signal used to keep at its value the instruction for the distance between the optical apparatus and the reference line, and in that the width of the bright spot falling on the receiver constitutes an adjustment signal used for the control of the transverse movements of the optical apparatus in relation to the reference line.